Analyze Weapons and LPCs:At the cost of one Gamma/Beta/Alpha core per Tier 1/2/3 weapon or fighter LPC, the omnifactory will scan them for future production. To use cores simply put them in the Omnifactory's storage.

Build Weapons:Weapons can be build by buying them in the purchase screen. Multiple weapons of the same type can be queued in sequence up to the stack amount present in the purchase screen. This will begin the construction process and after a time period dependent on size and tier the weapons will be deposited into storage. This process consumes resources including metal, rare metal, volatiles, and fuel.

Build LPCs:Fighter LPCs can be build by buying them in the purchase screen. Multiple LPCs of the same type can be queued in sequence up to the stack amount present in the purchase screen. This will begin the construction process and after a time period dependent on size and tier the LPCs will be deposited into storage. This process consumes only transplutonics but is significantly more time consuming than weaponry construction.

Analyze Ships:At the cost of one Gamma/Beta/Alpha core per Frigate/Destroy/Cruiser and 5 Alpha cores per Capital, the omnifactory will scan them for future production. To use cores simply put them in the Omnifactory's storage.

Build Ships:Ships can be build by buying them in the purchase screen. This will begin the construction process and after a time period dependent on size and fleet points the ship will be deposited into storage. This process consumes resources including metal, rare metal, organics, volatiles, and heavy machinery.

Order Ships:Pay a premium to have the sector's many markets search for you. At a markup between 25% and 375%, depending on the difficulty of acquisition, have ships from any market in the sector delivered to your storage.

Version 2.2.5: (August 31, 2017)================================Fix for lower resolutions.No longer able to replicate D-modded vessels.Misc fixes.Autofactory market description explains how to use the factory.

Version 2.1.2: (June 5, 2017)================================Added new option to omnifactory interaction. Displays all weapons the omnifactory has data for. Clicking on a weapon displays the resource requirements.Reworked resource requirements.Fixed a few bugs in the settings.

Version 2.1.0: (June 4, 2017)================================Added new option to omnifactory interaction. Displays all ships the omnifactory has data for. Clicking on a ship displays the resource requirements.

I don't know whether the question's already answered, but where will the mod put the omnifactory?

It currently puts it in orbit of Jangala. It will eventually (Once I've gotten enough feedback) be moved to a random uninhabited system, although the config option to spawn it in Corvus will still be present.